The spillways cannot handle the huge amount of inflow, so the earthen dam will over top (as shown above) and the dam has a very large risk of failing completely AT ANY TIME, both due to over topping, plus the pressure of water on BOTH sides of dam softening and weakening the structure of the dam itself. Earth erodes FAST once the water starts cutting, undercutting or following cracks, holes or fissures inside the earth..